1. Field of the Invention
The present invention relates to a Positive Temperature Coefficient (PTC) rod assembly and a preheater incorporating the same, and more particularly, to a PTC rod assembly and a preheater incorporating the same, in which not only a positive terminal but also a negative terminal are provided so that the PTC rod assembly can be used stably even when a high voltage is applied thereto, and in which a short-circuit preventing means is provided to prevent a short circuit from occurring between the two terminals due to contact.
2. Description of Related Art
A typical vehicle has a heating apparatus that heats the interior of the vehicle or removes moisture or frost from the windshield of the vehicle using the thermal energy of coolant, which is heated by heat generated from the engine of the vehicle.
In the heating apparatus, since the coolant, which flows around the engine after the engine is started, is introduced into a heater, it takes a great deal of time to heat the coolant and to subsequently heat the interior of the vehicle. Accordingly, there is a problem in that a driver and/or passenger(s) may be required to stay in the cold interior of the vehicle for a certain period of time even after the engine has been started.
In order to solve this problem, preheaters are used. As a representative example, preheaters incorporating a Positive Temperature Coefficient (PTC) element therein are generally used.
The PTC element is a semiconductor element that exhibits a positive temperature characteristic, in which electrical resistance increases sharply at the Curie temperature or higher. The PTC element has a self-temperature control function, i.e.; it remains at a constant heating temperature irrespective of the surrounding temperature when a voltage is applied thereto. Since this characteristic of the PTC element is advantageous when utilized as a heating element, fields to which the PTC element is applicable as a heating element of a heater are expanding.
FIGS. 1 and 2 show a PTC rod assembly of the related art.
As shown in FIGS. 1 and 2, the PTC rod assembly 1 of the related art includes an elongated first PTC rod 100, which has a channel defined therein, and a second PTC rod 200, which is coupled with the first PTC rod 100 to close the opening of the channel of the first PTC rod 100. A positive terminal 400 is placed inside the first PTC rod 100 and is enclosed by an insulator such that it does not contact the first PTC rod 100. PTC elements 500 are interposed between and in contact with the positive terminal 400 and the second PTC rod 200. Heat transfer blocks 600, which are made of a material exhibiting high heat conductivity, are in contact and coupled with the positive terminal 400.
The PTC element 500 is configured to generate heat when electrical power is applied thereto, in which one side of the PTC element 500 is in contact with the positive terminal 400 and the other side of the PTC element 500 is in contact with the second PTC rod 200, which serves as a negative terminal. Here, since the first PTC rod 100 and the second PTC rod 200 are in contact with each other, not only the second PTC rod 200 but also the first PTC rod 100 serves as the negative terminal. In addition, the insulator of the positive terminal 400 has expanded portions 320 and 340 at opposite ends thereof. The expanded portions 320 and 340 are in close contact with the inner surfaces of the first and second PTC rods 100 and 200 when the first and second PTC rods 100 and 200 are coupled with each other. Therefore, the inner space defined by the first and second PTC rods 100 and 200 are closed by the expanded portions 320 and 340.
In this fashion, the first and second PTC rods 100 and 200, which enclose the PTC elements 500 and the positive terminal 400, serve as the negative terminal.
However, in the PTC rod assembly 1 of the related art as described above, the first and second PTC rods 100 and 200, serving as the negative terminal, are exposed to the outside and are thus vulnerable to a short circuit by contact with other components. The PTC rods 100 and 200 can be grounded in order to prevent this problem. However, they are still electrically instable when a high voltage is applied thereto.
The information disclosed in this Background of the Invention section is only for the enhancement of understanding of the background of the invention, and should not be taken as an acknowledgment or any form of suggestion that this information forms the prior art that would already be known to a person skilled in the art.